\begin{table}%t1
%\centering
\par
\caption{\label{tab:constants}Instrument inter-calibration constants using the \hp as reference.}
\small  \begin{tabular}{l r@{}l}
\hline \hline
Instrument  & \multicolumn{2}{c}{Constant} \\
\hline
\lecs & 0.814  &~$\pm$ 0.008 \\
\mecs  & 0.970  &~$\pm$ 0.003 \\
\pds     & 0.857  &~$\pm$ 0.004 \\
\hline
\end{tabular}
\end{table}